In a large bowl, whisk together flour, brown sugar, baking powder, baking soda, salt, cinnamon, nutmeg, cardamom, ginger, and orange zest.
In another bowl, whisk together milk, vanilla, and eggs. Pour into dry ingredients and stir well to combine, until few lumps remain.
Let rest for 15 minutes. Meanwhile, preheat your waffle iron.
When ready to cook the waffles, stir the melted butter into the batter. Scoop batter into the waffle iron and cook according to iron specifications. Serve immediately.